1988-1991 Ford Mustang 5.0 EEC-IV Wiring Diagram - 60-Pin ECU Pinout & Colors

This document is a Ford EEC-IV engine control wiring diagram labeled "88-91 EEC Wiring Diagram" (credited to "tmoss"). It maps the 60-pin EEC processor connector to all major engine-management circuits, listing each pin number, signal name, and wire color/gauge, e.g., pin 50 MAF (Dark Blue/Orange 18ga), pin 47 TP (Dark Green/Light Green 18ga), pins 37/57 VPWR (Red 14ga), pins 40/60 PWR GND (Black/Light Green 14ga). It shows sensor wiring for the MAF, VSS, left and right HEGO oxygen sensors, ECT, TP, ACT, MAP/BP, and EVP sensors, plus the self-test connector, self-test input (STI), and malfunction indicator light (MIL). Actuator circuits include all eight fuel injectors (pins 58, 59, 12, 13, 14, 15, 42, 52), the idle speed control (ISC) bypass air solenoid, EGR vacuum regulator (EVR), canister purge (CANP), and Air Management 1/2 (AM1/AM2) solenoids. Relay and power distribution circuits are drawn for the EEC power relay, fuel pump relay, WAC (A/C) relay, starter relay, and battery, along with the neutral drive switch, clutch engine switch, neutral gear switch, TFI connector (with 22K-ohm SPOUT detail), A/C demand and cyclic pressure switches. A reader can identify any EEC pin's function and wire color for diagnosing or rewiring an 88-91 Ford 5.0 EFI harness.